Means and method for treating rubber springs



Nov. 21, 1950 A. s. KROTZ 2,531,059

MEANS AND METHOD FOR TREATING RUBBER SPRINGS Filed Feb. 12, 1944inmfbll... fi UT? 515550. 2

Patented Nov. 21, 1950 MEANS AND METHOD FOR- TREATING RUBBER-SPRINGSAlvin S. Krotz, Akron, Ohio, assignor to The B. F.

Goodrich Company, blew York, N. Y., a corporation of New YorkApplication February 12, 1944, Serial No. 522,079

I 6 Claims. 1

This invention relates to the treatment of springs of elastic rubber orother rubber-like material.

Torsion springs, comprising a substantially rigid supporting member, asubstantially rigid loading member, and a body of elastic deformablematerial such as soft vulcanized rubber or other rubber-like materialbetween the supporting and loading members and bonded thereto asbyvulcanization, are advantageous especially in providing both the supportof a vehicle and the cushion for the ride.

It has been found that for a short period after installation and initialloading of such torsion springs, the cushioning material takes the majorpart of, if not substantially all, the permanent set or apparentcreepage it will undergo in service, and a take-up adjustment after ashort period of use has ordinarily been'desirable.

The present invention aims to overcome, prior to installation of thespring, its tendency to creep in use, and to provide convenienttransportable means and novel procedure for presetting the springsbetween manufacture and installation.

Objects of the invention are to provide readily transportable means orapparatus for conveniently preloading the springs, preferably transtionthereof, parts of the apparatus and the spring being broken away andparts being shown .in section.

Fig. 2 is a cross-sectional view taken on line 2-2 of Fig. 1. i

Fig.- 3 is a side elevation,- with parts broken away and parts shown insection, of another spring, showing a modified form of presetting means.

Fig. 4 is a similar view showing a further modification of thepresetting means and a spring of different construction, parts beingbroken away.

g. 5 is an end view of Fig, 4.

Fig. 6 is a longitudinal sectional viewof another modification of thesetting means and a diii'erent form of spring.

Fig. 7 is a perspective view of another modification, in which settingmeans is provided for two, springs in combination.

In accordance with the invention the spring is torsionally loaded aftermanufacture and held under such torsional load fora period prior toinstallation to reduce the tendency to creep in use, and readilytransportable means are provided for holding the spring under suchtorsional load and, optionally, for adjusting such load, and the springmay be subjected to heat while held in loaded condition to enhance theeffectiveness of the treatment. In the illustrative embodiments shown inthe drawing, the load-holding or restraining means generally comprisesmeans for detachably engaging the supporting and load ing members of thespring for holding them with relation to each other in torsionallyloaded relation, and may include means for adjusting the torsional load.Such restraining means may assume Various forms depending somewhat uponthe construction of the spring, and several different forms of means areillustrated.

Referring to Figs. 1 and 2, which show one form of spring andrestraining means and con venient mechanism for placing the spring underload, the inner member In of the spring comprises a tubular metal shafthaving a key slot 45 in at least one end thereof extending axially ofthe shaft. The outer member comprises a pair of half-round shell members13, id, having their axial margins normally spaced from each other todefine longitudinally extending spaces l5, l6 therebetween. In useeither of the inner and outer members may be the supporting member whilethe other may be the loading member.

An annular body ll of elastic deformable material, such as softvulcanized rubber or similar rubber-like cushioning material capable ofangular distortion is located between the inner and outer member and isadhered thereto, as by a vulcanized bond. Angular rotative movement ofthe loading member with respect to the supporting member will place thedeformable body under torsional loading. The particular spring shown hasone longitudinal margin E8 of one of its shell members extendingtangential to the curved portion thereof so as to provide a radiallyraised shoulder for holding the shell in place when mounted by abutmentagainst a shoulder of the bore in which it is seated. Torsional loadingof this spring in a direction to press such raised margin (3i;llmierentially against a shoulder, not

only prevents rotation of the shell by reason of the shearing strengthof the metal, but also by reason of increased friction, due to thetendency of the metal shell to unwind under the tangentially appliedload, the shell acting as a selfenergizing brake against its confininghousing. The projecting margin l8 may also be utilized to preventrotation of the outer split shell under torsion during a pre-loadingoperation, as hereinafter described.

The apparatus illustrated in Fig. 1 is a convenient means forpre-loading the spring and comprises a supporting cradle l9 adapted toengage the outer shell of the spring. A clamping strap 26 has slottedears 2|. Swing bolts 22 are pivoted to the cradle at each side thereofas by a pin 23 extending through ears'24 of the cradle. The bolts extendthrough the notches in the ears 2| of the strap 29 and'have nuts 25threaded thereon whereby the strap may be drawn about the spring, theslots of the clamp ears permitting the bolts to be swung aside when thenuts 25 are turned back a few turns, thereby quickly releasing restraintof the spring.

A spindle 26 is journaled in brackets 21', 28 for rotative and axialmovement in alignment with the spring. It has a keyway 29 formedtherein. A worm gear 36 is slidably mounted on the spindle but isconfined laterally between brackets 21, 28 and has a ke 3| adapted toengage the keyway 29. A worm 32 meshes with Worm gear and drives thespindle from any convenient source of power (not shown).

For moving the spindle axially, a shifter fork 35 is pivotally mounted,as at 36, to bracket 28 and engages between collars 31, 38 fixed tospindle 26. A locking pin 39 is adapted to engage aperture 40 in theframe 4| of the apparatus, on which the cradle l9 and brackets 21, 28are supported, to lock the spindle in advanced or retracted positions.

For rotating the inner member of the spring, such inner member is formedwith an axially extending notch or other driving means adapted to beengaged by a pin or key 46 or other driving means on spindle 26 and thespindle may have a reduced end 4'? adapted to enter the bore of theinner member. The key 46 does not extend beyond the outer face of theinner member so that a retaining means may be slipped over the innermember, or removed therefrom without interfering with the lockedengagement of the spindle and the inner member.

For retaining the inner and outer members after loading of the cushionbody, a retainer 59 is provided. This retainer is adapted to beremovably secured over the inner and outer members in any desiredposition of loading. In the form of retainer shown in Figs. 1 and 2, theretainer has a bore 5| adapted to slide over the body of the spindle 26and the inner spring member, and has a counter bore 52 adapted to slideover the outer spring members axially and to limit rotation with respectthereto. Where the outer spring members have an axially projectingshoulder M3, the retainer may be formed with driving notches 53, 54adapted to receive such shoulders and to engage them by rotativeadjustment of the retainer. A set-screw 55 is threaded through theretainer to clamp the retainer to the inner spring member. Thearrangement is such that the retainer may be slipped axially over theend of the spring. With e p n clamped to the cradle, the spindle 2s maybe advanced so that its key enters the driving slot 45. The set screw 55may be backed off and the spindle 26 rotated the desired amount to loadthe cushion body of the spring. The set screw may then be tightened andthe spindle 26 withdrawn leaving the spring under load.

When it is desired to change the load after the retainer is in place, aretainer such as that illustrated in Figs. 4 and 5 may be employed. Herethe retainer comprises a cap 69 axially slotted as at GI, 62 and adaptedto be slipped axially over the outer member of a spring, and a separatecollar 63 is adapted to slide over the inner member of the spring. Anear 64 is formed on the cap and an arm 65 is formed on the collar 63. Ascrew 66 is threaded through the arm 65 and impinges against the ear 64.For securing the collar 63 to the inner spring member, means, such as apin 61 passing through aligned openings in the collar and the innerspring member, is provided. The spring shown in Figs. 4 and 5 with thisretainer, has projecting flanges 68, 69, 10, H, at the margins of itsouter shell members, which engage the opposed slots SI of the cap. Theretainer may be secured over those fiangs and the collar 63 may besecured to the inner member either before or after loading the cushionbody. When it is secured before loading, loading is accomplished byrotating screw 66 and when the loading means of Fig. 1 or a similarmeans is employed to load the spring torsionally, the spring may besecured after loading and the screw 66 then used to increase or decreasethe torsional load.

In the retaining means illustrated in Fig. 3, a one-piece retainer cap15 has a splined or serrated bore 16 adapted to slidably engage over asplined surface I! of the inner spring member, and a counterboredportion 18 adapted rotatably to engage over the outer spring member.This from of spring and retainer may be assembled by use of .a loadingmeans similar to that of Fig. 1. the spindle having a serrated cup tofit over the end of theinner spring member instead of engaging themember from within. After loading, screws 80, 8| threaded through theretainer may be tightened against the outer members 82, 83 of thespring.

In the spring shown in Fig. 6, an outer shell 85 of metal has integralinwardly turned ears 86, 87, and the inner member 88 is tubular and issupported from within by a spider 89 having a serrated bore 90. Theretaining means comprises a serrated plug 9| adapted to fit the serratedbore and having arms 92 extending radially outwardly thereof. The arms92 have apertures in alignment with the ears 86, 8! and rivets or pins93 may be employed to secure the arms to the ears after loading thecushion body torsionally.

After application of the retaining means, the spring may be stored ortransported with the retainer in place so that creep or permanent set ofthe cushion material is conveniently accomplished during storage andshipment and the spring is ready to install at their destination in acondition for minimum tendency to creep in use.

The invention also makes possible immediate loading of the cushioningbody after molding thereof and before the molding heat has beendissipated from the spring so that the heat may be utilized toaccelerate removal of creep and permanent set, Too rapid a loss of heatmay be prevented by packing the loaded spring in a closed container ofheat insulating material so that heat treatment is extended.

In some cases it may be desirable to stress a plurality of springstogether, for example in pairs, in accordance with the embodiment ofFig. 7. Here, a pair of springs I and Hill are of a kind havingrespective inner shafts I02, )3, outer sleeves I54, I05, and bodies H16,fill of resilient rubber or other rubber-like material interposed andbonded to the respective shafts and sleeves, and provided with extendingarms H18, H39 integral with the respective sleeves I04, 105. The shaftsof the two springs are locked together as by a brace or bracket memberH0 having apertures to receive the shafts and set screws Hi and H2adapted to bear against the shafts. A second brace or bracket member H3has apertures receiving the other ends of the two shafts and may alsohave set screws, indicated at H4, H5, for engaging the shafts to assistin holding them against rotation. These set screws Hi, H5 may however beomitted when the shafts are locked at their other ends.

An end plate 8 i6 is adapted to be applied to the ends of the arms 108,I99 when the latter are swung to a position of adjacency to stress thesprings rotatively, one clockwise and the other counter-clockwise. Theend plate H6 may be connected with the brace i it by an extension H!which fixes the springs in definite relative positions. Fastening meanssuch as screws H8, H9 hold the arms to the end plate H6. In this mannerthe pair of springs is stressed as a compact transportable unit, andinasmuch as both springs may thus be stressed and retained under thesame conditions and for the same period of time, this is of advantageespecially in providing matched springs in pairs for the two frontWheels of the same vehicle, or the two rear wheels thereof.

In the use of any of the retaining and packaging means shown, the springmay be torsionally loaded directly after vulcanization of the cushionbody or later if desired, and the retainer applied without releasing theloading force, and the spring may be transported and stored in loadedcondition. Thereafter upon installation the retainer may be removed andreturned for reuse on another spring. If desired in some cases thespring may be installed without relieving the spring of its torsionalloading, the weight of the vehicle being applied before the release, sothat the spring remains stressed continuously from manufacture throughtransportation, storage, installation and on into use.

Variations may be made without departing from the scope of the inventionas it is defined by the following claims.

I claim:

1. The method of treating an assembly of parts for providing a torsionspring having inner and outer supporting and loading members with acushioning body of resilient rubber-like material therebetween andbonded thereto to reduce tendency of the spring tocreep rotatively inuse, which method comprises subjecting the assembly to a molding andvuloanizing operation under heat and pressure, loading the cushioningbody while it still retains heat of the molding and vulcanizingoperation but prior to installation of the spring by relative rotativedisplacement of said members, securing the members in their displacedrelation, insulating the spring to delay cooling of the spring over aperiod of time preceding the installation of the spring sufficient toreduce the tendency to creep after installation, and installing thespring after the tendency to creep has been reduced.

2. A torsion spring package transportable between manufacture andinstallation comprising a spring having inner and outer members with abody of resilient'rubber-like material therebetween and bonded byvulcanization thereto, and means transportable with the spring forengaging said inner and outer members of thespring to maintain the innerand outer members rotatively displaced relative to each other with saidresilient material in a relatively stressed condition, said meanscomprising a holding structure mounted in gripping relation to the innermember and extending radially outward at an end of the spring and havingan outer portion mounted in gripping relation to the outer member of thespring for resisting relative rotation of said members in thetorsionally stressed condition.

3. A torsion spring package transportable between manufacture andinstallation comprising a spring having inner and outer members with abody of resilient rubber-like material therebetween and bonded byvulcanization thereto, and means transportable with the spring forengaging said inner and outer members of the spring to maintain theinner and outer member rotatively displaced relative to each other withsaid resilient material in a relatively stressed condition, said meanscomprising a holding structure having a cupped portion overlying theouter member of the spring at an end thereof in gripping relation tosaid outer member and having a tubular portion engaging over the innermember of said spring at an end thereof and nonrotatively securedtheretofor resisting relative rotation of said members in the torsionallystressed condition.

4. A torsion spring package transportable between manufacture andinstallation comprising a spring having inner and outer members with abody of resilient rubber-like material therebetween and bonded byvulcanization thereto, and means transportable with the spring forengaging said inner and outer members of the spring to maintain theinner and outer member rotatively displaced relative to each other withsaid resilient material in a relatively stressed condition, said meanscomprising a holding structure having a flange secured to the outermember of the spring at an end thereof and having a portion extendingwithin the inner member of said spring and secured thereto innon-rotative relation thereto for resisting relative rotation of saidmembers of the spring in the torsionally stressed condition.

5. A torsion spring package transportable between manufacture of torsionsprings and installation thereof, said package comprising a pair oftorsion springs each comprising an inner shaft and an outer sleevestructure and a body of resilient rubber-like material therebetween andbonded by vulcanization thereto with the sleeve structure of each springhaving a projection extending transversely thereof, said springs beingdisposed in side-by-side relation with the shafts and sleeves generallyparallel to one another, and means transportable with the springs forlooking the shafts of the springs against rotation and for locking theprojections in positions to main-' tain the sleeve structure of eachspring rotatively displaced relative to its shaft with saidrubberassumes like: material: of each' spring? ina rotati'velystressedicondition, saidimeans comprising a holding structure at an endof said springs with means associated therewitlr for locking saidshaftsagainst' rotation with respect to said holding. structure; and asecond holding structure connecting said; projections to resist rotationof said sleeve structures relative.- to said shafts when said springsare'held: b said holding structures int a condition of stress tending tocause such rotation.

61 Av torsion spring package transportable between manufacture oftorsion springs and installationtheeof, said package comprising a pairof torsionsprings each comprising an inner shaft and: an: outer sleevestructure and a body of resilient rubber-like material therebetween' andbonded byv-ulcanization thereto with the sleeve structureof each springhaving a projection extending transversely thereof, said springs beingdisposed in side-by-siderelation with the shafts and sleeves generallyparallel to one another, and means transportable with the springs forlocking the shafts of the springs against rotation and for looking theprojections in position to maintain the sleeve structure of eachspringrotativel'y displaced relative to its shaft. with saidrubber-likematerial of each. spring in a rotatively stressed REFERENCES CITED Thefollowing references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date:

1,358,878- Rinn, Jr -Nov. 16, 1920 1,951,805 Ferris Mar. 20-, 19341,951,825 Ferris Mar; 20, 1934 1,964,735 Knox et-al July 3, 1934 23051864 Knoxet a1 Aug. 25,1936 2,110,783 Welker Mar. 8, 1938 2,215,134Rehnberg y Sept. 17, 1940 2,231,769 Merrill Feb. 11, 1941 2,286,609Ledwinka June 16, 1942

1. THE METHOD OF TREATING AN ASSEMBLY OF PARTS FOR PROVIDING A TORSIONSPRING HAVING INNER AND OUTER SUPPORTING AND LOADING MEMBERS WITH ACUSHIONING BODY OF RESILIENT RUBBER-LIKE MATERIAL THEREBETWEEN ANDBONDED THERETO TO REDUCE TENDENCY OF THE SPRING TO CREEP ROTATIVELY INUSE, WHICH METHOD COMPRISES SUBJECTING THE ASSEMBLY TO A MOLDING ANDVULCANIZING OPERATION UNDER HEAT AND PRESSURE, LOADING THE CUSHIONINGBODY WHILE IT STILL RETAINS HEAT OF THE MOLDING AND VULCANIZINGOPERATION BUT PRIOR TO INSTALLATION OF THE SPRING BY RELATIVE ROTATIVEDISPLACEMENT OF SAID MEMBERS, SECURING THE MEMBERS IN THEIR DISPLACEDRELATION, INSULATING THE SPRING TO DELAY COOLING OF THE SPRING OVER APERIOD OF TIME PRECEDING THE INSTALLATION OF THE SPRING SUFFICIENT TOREDUCED THE TENDENCY TO CREEP AFTER INSTALLATION, AND INSTALLING THESPRING AFTER THE TENDENCY TO CREEP HAS BEEN REDUCED.
 2. A TORSION SPRINGPACKAGE TRANSPORTABLE BETWEEN MANUFACTURE AND INSTALLATION COMPRISING ASPRING HAVING INNER AND OUTER MEMBERS WITH A BODY OF RESILIENTRUBBER-LIKE MATERIAL THEREBETWEEN AND BONDED BY VULCANIZATION THERETO,AND MEANS TRANSPORTABLE WITH THE SPRING FOR ENGAGING SAID INNER ANDOUTER MEMBERS OF THE SPRING TO MAINTAIN THE INNER AND OUTER MEMBERSROTATIVELY DISPLACED RELATIVE TO EACH OTHER WITH SAID RESILIENT MATERIALIN A RELATIVELY STRESSED CONDITION, SAID MEANS COMPRISING A HOLDINGSTRUCTURE MOUNTED IN GRIPPING RELATION TO THE INNER MEMBER AND EXTENDINGREADIALLY OUTWARD AT AN END OF THE SPRING AND HAVING AN OUTER PORTIONMOUNTED IN GRIPPING RELATION TO THE OUTER MEMBER OF THE SPRING FORRESISTING RELATIVE ROTATION OF SAID MEMBERS IN THE TORSIONALLY SRESSEDCONDITION.